It is generally known that tooth decay and periodontal disease are at least partially caused by plaque build-up on the surfaces of teeth and gums. Plaque is a sticky, translucent mass composed mainly of bacteria that are able to form long filamentous strands allowing the bacteria to adhere to smooth surfaces of the teeth and gums. These bacteria feed on dissolved sugars, sloughed skin cells, and tissue fluids. They produce waste products, acids and enzymes that are toxic to both tooth enamel and gingival tissues, including the gums, those gingival tissues immediately surrounding the teeth. If left undisturbed for 24-36 hours, the individual plaque bacteria develop into mature colonies that have the capacity to concentrate the acids, isolate them from dilution by the buffering action of saliva, and hold the acids against the tooth surface. If plaque build-up is chronic and sugar consumption is repetitive, the incessant acid insults first demineralize and then cavitate the enamel surface. This cavitation is the process we call dental caries or tooth decay. The toxic enzymes produced by plaque bacteria have the capacity to breakdown connective tissue holding gingival tissue together. If the plaque enzymes contact the gingival tissue of the sulcus area, the V-shaped crevice where the tooth and gum come together, the attachment of the gum to the tooth can loosen and a pocketforms. The depth of this gingival pocket is the pathologic barometer of the severity of periodontal disease.
Both of these pathologic processes (which together account for 98% of tooth loss) can be stopped effectively if plaque is not allowed to remain on the tooth long enough to develop mature colonies. Therefore daily thorough mouth cleaning can substantially prevent these oral diseases from causing tooth loss. Toothbrushing is the most successful widely practiced method of removing plaque from the mouth. The complex anatomy of the teeth and gums requires two distinct brushing motions to remove plaque effectively. Unfortunately, very few people ever master these two brushing motions, which are relatively complex and require a high degree of dexterity. The brushing motions also require more time than most people are willing to spend brushing their teeth.
The first brushing motion is a rolling or rotary brush motion beginning at the gum at the base of the tooth and continuing across the tooth to its biting surface. This rotary or rolling motion is known to be the most effective method of cleaning the tooth surfaces facing the spaces between the teeth known as the interdental spaces. The second brushing motion needed for thorough plaque removal is a series of rapid but very short vibratory strokes. To correctly execute the vibratory motion, the brush is placed along the gum line with some of the bristles gently inserted into the sulcus. The brush handle then is moved back and forth about one-eighth of an inch, with the bristle tips held stationary within the sulcus. This important vibratory motion removes plaque from the otherwise hard to reach sulcus.
Instead of using these effective brushing techniques, most people not only brush their teeth less effectively but actually brush in ways that have pathological consequences. For example, many people brush their teeth with a back and forth sawing motion. This reciprocating motion cleans the broad sides of the teeth but fails to clean in the interdental spaces. Many people try to perform the rotary or rolling motion but make the mistake of going too far with their brush stroke. They start on the upper gum line and brush down over upper teeth, the lower teeth and onto the lower gum line, or just the reverse. This has two pathological effects. First, gingival tissue is pushed away from the teeth, a practice that can lead to premature gingival recession. Second, mouth fluids are swept into the sulcus. Mouth fluids typically contain plaque-forming bacteria and, once lodged in the sulcus, are seldom removed because very few people outside of the dental professional community have mastered the complex, vibratory sulcus cleaning stroke.
The ideal electric toothbrush would safely simulate both rotary and vibratory brushing motions. Electric brushes have been designed using a rotary principle with spinning, cylinder-shaped brushes. Rotary toothbrushes having but one brush generally are provided with a reversible motor. The reversible motor is important because, in order to avoid sweeping mouth fluids into the sulcus and pushing gingival tissue away from the tooth, the brush has to spin in a downward direction against upper teeth and in an upward direction against lower teeth. Examples of such toothbrushes include Kurachi, U.S. Pat. No. 3,739,416; Grossman, U.S. Pat. No. 3,551,932; Koblanski, U.S. Pat. No. 3,829,922; Quint, U.S. Pat. No. 4,163,300; Fortenberry, U.S. Pat. No. 3,235,897; Poizat, U.S. Pat. No. 3,161,899; and Glynn, U.S. Pat. No. 2,279,982. Typically, brush direction must be changed many times during a brushing, and it is not easy to remember whether the brush is going in the correct direction relative to gum tissue.
Another arrangement that insures that bristles will be moved in the correct direction is the employment of two, parallel, cylindrical rotary brushes, located side-by-side but counter-rotating so as to rotate in opposite directions. The side of such a pair of rotary brushes on which the bristles are moving toward each other is applied to the teeth, the opposite side often being covered by a shield. By means of this arrangement, the lower gum and teeth are encountered by bristles that are sweeping upwardly, and the upper teeth and gum are encountered by bristles sweeping downwardly. Examples of such toothbrushes include Francolino, U.S. Pat. No. 3,800,350; Merkel, U.S. Pat. No. 2,124,145; and O'Rourke, U.S. Pat. No. 4,304,023. Smith, U.S. Pat. No. 4,313,237; and Caliendo, U.S. Pat. No. 3,925,841, show more complicated devices utilizing three rotary brushes, two adapted to sweep upwardly, one on either side of a row of teeth, and a third to sweep across the chewing surface of the teeth. These three brush designs solve the directional problem in that the brushes always rotate in the correct direction relative to the sulcus. However, the three brush arrangement tends to be fairly large and awkward to use for that reason.
Taylor, U.S. Pat. No. 3,512,201; and Taylor, U.S. Pat. No. 3,512,202, show toothbrushes that appear to be unique in providing for both a rotary brushing action and an independent, reciprocating motion of generally cylindrical brushes moving in a direction parallel to their longitudinal axes. Thus, only the Taylor toothbrushes provide for a powered administration to teeth and gums of both the rotary and vibratory brushing actions considered ideal for thorough plaque removal. The Taylor brushes utilize two motors, one to rotate the brushes and a second to reciprocate them axially.
The art is not cognizant of an electric, rotary toothbrush in which the desirable rotary bristle motion and alternatively selectable reciprocating, axial motion is achievable by use of a single motor.